Furnace lining, especially of highly heated metallurgical furnaces and particularly to linings of furnace gas ports



i 2,134, CAL FURNACE PoR J, GODENNE. 4 ALLY oF HIGHLY HEATED METALLURGIvULARLY LININGS oF FURNACE GAS F' Dec. 11, 1935 To led EsPEcI PLRTIGoct. 25,1938.

' FURNAQE LINING,

' AND Y/ J y//// dem?a QM@ Patented Oct. 25), 1938 FURNACE LINING,ESPECIALLY F HIGHLY HEATED METALLURGICAL FURNACES AND PARTICULARLY T0LININGS OF FURNACE Gas Pon'rs Jean Godenne, Anzin,v France ApplicationDecember 11, 1935, Serial No. 53,967 y f In France February 14, 1935 4Claims.

'Ihe present .invention relates to gas ports of highly .heatedmetallurgical furnaces, such as basic Siemens-Martin furnaces.

'I'he .gas ports of highly'heated furnaces, in 5 which the slag questionplays a considerable part, are gradually destroyed during the operationof the furnaces. Since the furnace linings also have in part towithstand considerable wear they must constantly be entirely renewedafter a certain l0' amount of destruction has taken place, in order toenable further operations to be carried out.

It has not hitherto been possible to produce a furnace constructionmaterial, which will'stand to all the stresses and strains resultingfrom the l5 high temperatures employed, the attacks by scorifyingsubstances and mechanicalstrains. Consequently'the best way out of thediiculty hitherto has always been to employ a furnace material, whichensured the furnace functioning for a cer- 20 tain time. In the case ofhighly heated metallurgical furnaces, for example basic Siemens-Martinfurnaces, silica bricks have been used for the construction of thegas-ports. These silica bricks however fuse comparatively rapidly underthe in- Cil ticles of ferrie oxide and lime carried along with theame.

Attempts have also already been made to replace the silica bricks bybricks of other, very highly refractory materials, particularly highlyrefractory oxides or oxide mixtures, which in turn, owing to theirchemical nature-in contravdistinction to the silica masonry-do not formany easily melting compounds with the attacking substances and which onthe other hand also have so high a .melting point, that the lining doesnot reach the point of fusion at the temperatures prevailing in thefurnace. A satisfactory result could however not-be obtained by the useof these highlv refractory building materials. In this case alsodestruction of the masonry tookplace after a more or less long time.This destruction is effected by the migration of the slag particles intothe bricks. Consolidation of the masonry takes 45 place, whereby thelining breaks oil in scales to a more or less considerable thicknesswhen changes in temperature take place. 'I'he destruction is furtherpromoted owing to the fact that the bricks made of the aforesaid highlyrefractory materials :.o cannot be satisfactorily welded. Finallygasports, particularly those made of magnesite bricks, show astrongtendency to form slag deposits, whereby the free passage of the gases ishindered, which in turn gives rise to disturbances ,.5 in operation.

fluence of the high temperatures and of the par- 'I'he object of thisinvention is to provide gas ports, the construction of whichconstituteslan essential impr-ovement of the methods of constructionhitherto used and which has a long life.

According to the invention the core or the 5 main mass of the gas portsis made of a refractory material of high thermal resistance, for eX-ample highly refractory -oxides and oxide mixtures. In these parts,which, as well as being y subjected to high temperatures, are alsosubjectl0 ed to the above described detrimental scorifying action, themain mass is supported by a layer of refractory material of lowermelting point, but of higher physical resistance or tenacity at hightemperatures and which has not tendency to form l5 slag deposits.

Owing to the fact that the gas ports are thus `made of a plurality ofmaterials, each of'which has denite functions assigned thereto, i. e.th'e fulfilment of all functions is distributed over a plurality ofmaterials, it is possiblel so to construct each individual part of thegas ports for the function thereof that it is particularly capable ofstanding up to the.. requirements in question.

mass may be made compact and mechanically strong at high temperatureswithout regard to the capability of resisting abrupt changes intemperature and conversely the inner surface of the arch may be made tofulfil its particular function of a construction adapted for supportingthe main mass.

The invention will now be described by Way of example in relation to agas port for a basic Siemens-Martin furnace with reference to theaccompanying'drawing, wherein- Fig. 1 is a longitudinal section throughthe gas port, and

Fig. 2 is a cross section along the line 2-2 of Fig. 1 as viewed fromthe front of the gas port.

According to this embodiment the arch l of the gas port a is made ofsilica bricks, which may be made in varying size depending upon thedimensions of the' furnace. is, however, maintained fairly thin inrelation to the entire mass of masonry between the gas port a and theair port b. Above this arch I of silica. bricks a thinner layer (about 1cm.) of a rie mortar 3 of neutral material, Afor example chromite, isdisposed and the mass 2 defined above as 50 main mass, which consistslof highly refractory materials, for example bricks or tamping masses ofmagnesiteor other highly refractory oxides, is applied thereto. 'I'hebricks of the mass 2 are joined together by a layer, which eects aninti- Thus, for example, the highly refractory main '25' The layer ofsilica bricks CII mate bond on fusion, for example thin steel strips 8.When using tamping masses it is advisable to add suitable quantities ofa flux, which under the action of the furnace temperature forms acompact and mechanically resistant mass from the highly refractory mainmaterial. The upper surface of the mass 2 facing the air port is coveredwith a chromite layerV 4. The air port b is in turn provided with anarch of silica bricks 5. The bottom of the gas port a is indicated as 6.

The thickness of the arch l of silica bricks may diminish towards thetongue l and conversely may increase in the reverse direction.

Even when the thickness of the supporting arch is relatively small it isprotected from theinfluence of the names and slags by the main mass ofthe burner. This mass may be made of refractory materials which are moredificultly fusible and more difflcultly soluble in slag than silica`bricks.

The arrangement illustrated practically avoids reactions which mighttake place at elevated temperature between magnesite masses or neutralmasses and the acid substances, insofar as acid substances are used forthe construction of the inner arch. Owing to the high melting point ofthe basic masses disposed above the arch, fusion can scarcely beobserved and reactions of these highly refractory products with thosedisposed beneath are reduced to a minimum. In operation the supportingarch fuses back more rapidly than the main mass, its products of fusioncan fall down side by side and accordingly do not interact with oneanother. Since the arches, as hereinbefore stated, are only of slightthickness, the proportion of fused products also is smaller andaccordingly their action on the bottom of the ports is also slight, inany cases much slighter than if the entire mass of the gas ports were toconsist of silica masonry.

The employmentof the described silica arch furthermore enables the innercross section of the gas port a to be maintained. In the course of thefurnace operation only slow widening takes place.

In the embodiment illustrated the tongue 'l is the part which issubjected to the highest temperature. Silica masonry at this point wouldfuse much more rapidly than the basic mass 2. For this reason the uppermain part thereof is made of highly refractory material and a thin layerof silica masonry is present only on its lower side. Under the influenceof the high temperatures here prevailing the silica bricks commence tofuse and disappear on the tongue to a slight depth of, for example, 5 to10 cms. If the considerably more resistant tongue portion made ofmagnesite melts or crumbles, a portion of the silica bricks will alwayssimultaneously fuse off,

so that during the course of the furnace operation, the highlyrefractory main mass will always project slightly beyond the silica massdisposed beneath and protect the same. The projecting part of the highrefractory main mass is of so slight a thickness, that mechanicalstrains can scarcely take place.

Owing to the fact that the piers or pillars of the furnace may be madeof magnesite products or other masses having a hightemperatureresistance and that the mass of the silica brick arch layer is only ofrelatively small thickness, the fused products of which accordingly onlyslightly attack the bottom of the gas channel, the Wear of the gas portsis much slower, less intense and more uniform than with otherconstruction materials. Uniform furnace operation from the start to nishis accordingly ensured.

In rst line the new construction is adapted for such parts of furnaceswhich support other parts of the furnace construction or must carrythemselves, i. e. doors, openings, crowns or the arches thereof, andwhile the lining is subjected to the action of high temperatures andscorifying agents.

.I claim:

1. Gas ports for Siemens-Martin furnaces and other highly treatedmetallurgical furnaces comprising a. gas channel and an air channeldisposed ab' ve the gas channel, and a Wall separating said gas channelfrom said air channel, the main mass of said Wall consistingsubstantially of highly refractory oxidic material, the surface of saidwall facing said gas channel consisting of a relatively thin layer ofsilica masonry and the surface of said Wall facing said air channelconsisting of a layer of chromite.

2. Gas ports according to claim l wherein the main mass of said wallconsists substantially of a mass selected from the group consisting ofmagnesite masonry and magnesite tamping masses and the surface of saidwall facing said gas channel consists of a relatively thin layer ofsilica masonry and a layer of neutral refractory material is disposedbetween said main mass and said silica masonry.

3. Gas ports according to claim 1 wherein the main mass of sai-d wall isconstructed of magnesite bricks intimately joined together byinterposing thin steel strips and burning, and the surface of said wallfacing said gas channel consists of a relatively thin layer of silicamasonry.

4. Gas ports according to claim 1 wherein the main mass. of said wall isconstructed of highly oxidic tamping masses having ya high mechanical

